Optical information recording medium and reproduction method

Abstract

In a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit (P 1 max) or a longest space (S 1 max) in a first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit (P 2 max) or a longest space (S 2 max) in the second pit row is defined as a second reflectance, the first pit row is formed such that the first reflectance becomes substantially identical with the second reflectance.

The invention claimed is: 
     
       1. An optical information recording medium comprising:
 a recording layer which includes (i) a first region in which information is recorded by a first pit row that includes a pit whose length is shorter than that of an optical system resolution limit of a reproduction device and (ii) a second region in which information is recorded by a second pit row that is made up of pits whose length is equal to or longer than that of the optical system resolution limit, 
 in a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit or a longest space in the first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit or a longest space in the second pit row is defined as a second reflectance, 
 the first pit row being formed such that the first reflectance becomes substantially identical with the second reflectance, and 
 the second region recording therein medium identification information for identifying a medium. 
 
     
     
       2. An optical information recording medium which is to be reproduced by a reproduction device that (i) emits reproduction light having a wavelength of 405 nm and (ii) includes an objective lens having a numerical aperture of 0.85, said optical information recording medium comprising:
 a recording layer which includes (i) a first region in which information is recorded by a first pit row that includes a pit whose length is shorter than 119 nm and (ii) a second region in which information is recorded by a second pit row that is made up of pits whose length is equal to or longer than 119 nm, 
 in a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit or a longest space in the first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit or a longest space in the second pit row is defined as a second reflectance, 
 the first pit row being formed such that the first reflectance becomes substantially identical with the second reflectance, and 
 the second region recording therein medium identification information for identifying a medium. 
 
     
     
       3. A method for reproducing an optical information recording medium recited in  claim 1 , said method comprising the step of:
 determining a reproduction condition based on the medium identification information which has been obtained by irradiating the second region with reproduction light. 
 
     
     
       4. A method for reproducing an optical information recording medium recited in  claim 2 , said method comprising the step of:
 determining a reproduction condition based on the medium identification information which has been obtained by irradiating the second region with reproduction light.